In the food industry today it can sometimes be of outmost importance to ensure that food items that are being conveyed form a sequence where the distance between adjacent food items is suitable for subsequent processing step. As an example, robots that are being implement today for generating batches of pre-fixed target weight of two or more food items require that a minimum distance is present between adjacent food items in order to work in the most optimal way and maximize the throughput. If this distance is below or above this limit the throughput of the robots and thus the processing is reduced. Another example is grading of food items into multiple of bins, where certain minimum distance must be present between the food items so that the mechanical arms that are associated with the conveyor systems can redirect the items passing by on the conveyer belt to the appropriate receiving bins.
A common solution to solve the above mentioned problem is to implement two conveyor belts with fixed ends that are running with different speeds so that the conveyed food items become accelerated along the conveyor belt. FIG. 1 shows a scenario where a first conveyor 101 and a second conveyor 102 are running with different speeds where v2>v1 and the incoming food items 103-105 have different lengths. At the interface between the first conveyor 101 and the second conveyor the acceleration causes that the distances between the items is increased as shown in FIG. 1b. 
The drawback with this method is that in case the length of the items is different as shown here it will not be possible to ensure even distances between the food items on the second conveyor 102. The distance d1 may be the most preferred distance i.e. that maximizes the throughput in the subsequent processing steps, whereas distance d2 is too long and causes a time delay in the subsequent processing step and thus reduces the throughput in the process.
Also, in case of two or more batches as depicted in FIG. 2, the space d1 between two batches shown in FIG. 2a will be increased to a distance d2>d1, which again results in an increased waiting time for the subsequent processing steps.
US 2003/0196871 discloses a device to correct uneven spacing of successive articles, where the device is capable of taking a single row of unevenly spaced articles on a first conveyor and ensure that the articles are more evenly spaced or more evenly stacked on a second conveyor. This is done by moving a noser of a first conveyor upstream or downstream so that the point of arrival for an article on a second conveyor may be moved upstream or downstream, thereby correcting the spacing of the articles on the second conveyor belt. As an example, the device can be implemented for any process where there is a shingling or stacking operation of e.g. cookies or crackers, causing the articles to overlap or shingle on the second conveyor belt. The first and the second conveyor belts may also be on the same level if the aim is change items that are unevenly on the first conveyor to become uniformly spaces them on the second conveyor without stacking.
There are however situations where the disclosure of US 2003/0196871 fails. This is as an example where food items such as fish fillets undergo a cutting process where a fish fillet is cut into several pieces that are lying next to each other, and where there is some distance, e.g. on average 30 cm, between adjacent fish fillets and where the requirement is to make an even distribution of the pieces with e.g. 5 cm distance there between. This may be of outmost importance where a subsequent packaging is performed by e.g. robots where such a spacing is the minimum spacing needed so that the robot arm has sufficient space to take only one piece at a time and to place is it a container. If the spacing is more than 5 cm the throughput/speed of the robot(s) will not be fully used and thus the throughput of the packing process will be reduced.
FR 2748461 A discloses a method and a device for transferring items such as biscuits from an infeed carrier to an outfeed carrier. The carriers are positioned one after the other and adapted to form a junction therebetween, which is borne by an upper mobile carriage in order to provide a variable transition front for the items. Both of these carriers are continuous carriers, guided by a set of deflection and/or tensioning rollers, and furthermore a lower mobile carriage is utilized for guiding the carriers. The two mobile carriages are connected by a continuous chain device, comprising two continuous chains and corresponding deflection pulleys or wheels placed lateral on either side of the carriages, whereby the upper and the lower mobile carriages are moved simultaneously by equal distances, but in opposite directions, when the variable transition front between the infeed carrier and the outfeed carrier is moved.
Due to the laterally disposed continuous chain device for moving the two mobile carriages, this prior art method and device implies a spacious and relatively complex arrangement. Furthermore, due to this space demand, such a prior art device will not be suitable for arranging two or more devices next to each other, e.g. in processing plants, etc.
Moreover, this device is designed for light items such as biscuits, where the carrying capacity is limited to the conveyor belt tension meaning that the more carrying capacity that is needed the more thick must the conveyor belt need to be. This would obviously be reflected in that the width of the transition front of the transfer system, between the two wheels, will be larger if the belt is larger. However, if the incoming food products are relative thin and/or bendable, e.g. fish fillet pieces, they can easily get stuck at the transition or simply fall down there between.
The inventor of the present invention has appreciated that there is thus a need for a conveyor system that is capable of converting uneven distances of incoming food items or batches to controlled distances such as even distances so as to optimize subsequent processing steps and thus maximize the throughput of the process and has in consequence devised the present invention.